This invention relates to an alkylation process using a family of related crystalline aluminosilicate zeolites, examples of which have been designated UZM-5, UZM-5P and UZM-6. These zeolites are structurally different from other zeolites.
Zeolites are crystalline aluminosilicate compositions which are microporous and which have a three dimensional oxide framework formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. One such process is the alkylation of aromatics with olefins and especially the alkylation of benzene with ethylene or propylene. The reaction between benzene and propylene produces mostly cumene. Cumene is an important industrial compound because it is a source of phenol, acetone, which are obtained by the oxidation of Cumene and subsequent acid-catalyzed decomposition of the intermediate hydroperoxide. Acid catalysts are used to catalyze this reaction with the most common catalysts being zeolites and particularly zeolite beta.
Applicants have synthesized a new family of crystalline aluminosilicate zeolites which have good activity for the alkylation of aromatics. These crystalline zeolitic compositions have a unique x-ray diffraction pattern and have an empirical formula on an anhydrous basis in terms of molar ratios of
Mmn+Rrp+Al(1xe2x88x92x)ExSiyOz
where M is at least one exchangeable cation selected from the group consisting of alkali and alkaline earth metals, xe2x80x9cmxe2x80x9d is the mole ratio of M to (Al+E) and varies from about 0 to about 1.2, R is a nitrogen-containing organic cation selected from the group consisting of quaternary ammonium ions, protonated amines, protonated diamines, protonated alkanolamines, quaternary alkanolammonium ions and diquaternary ammonium ions, and mixtures thereof, xe2x80x9crxe2x80x9d is the mole ratio of R to (Al+E) and has a value of about 0.25 to about 3.0, E is an element selected from the group consisting of Ga, Fe, Cr, In and B, xe2x80x9cxxe2x80x9d is the mole fraction of E and varies from 0 to about 0.5, xe2x80x9cnxe2x80x9d is the weighted average valence of M and has a value of +1 to about +2, xe2x80x9cpxe2x80x9d is the weighted average valence of R and has a value of +1 to about +2, xe2x80x9cyxe2x80x9d is the mole ratio of Si to (Al+E) and varies from about 5 to about 12. and xe2x80x9czxe2x80x9d is the mole ratio of 0 to (Al+E) and has a value determined by the equation:
z=(mxc2x7n+rxc2x7p+3+4xc2x7y)/2.
Specific members of this family of zeolites are UZM-5, UZM-5P and UZM-6.
This invention relates to a process for the alkylation of aromatic compounds using a new family of zeolites. Accordingly, one embodiment of the invention is a process for alkylating an aromatic compound comprising reacting under alkylation conditions and under at least partial liquid phase conditions an olefin with an alkylatable aromatic compound to provide an alkylated compound in the presence of a crystalline aluminosilicate zeolite having a composition in the as synthesized and anhydrous form in terms of mole ratios of the elements given by:
xe2x80x83Mmn+Rrp+Al(1xe2x88x92x)ExSiyOz
where M is at least one exchangeable cation selected from the group consisting of alkali and alkaline earth metals, xe2x80x9cmxe2x80x9d is the mole ratio of M to (Al+E) and varies from about 0 to about 1.2, R is a nitrogen-containing organic cation selected from the group consisting of protonated amines, protonated diamines, protonated alkanolamines, quaternary ammonium ions, diquaternaryammonium ions, quaternized alkanolamines and mixtures thereof, xe2x80x9crxe2x80x9d is the mole ratio of R to (Al+E) and has a value of about 0.25 to about 3.0, E is an element selected from the group consisting of Ga, Fe, Cr, In and B, xe2x80x9cxxe2x80x9d is the mole fraction of E and varies from 0 to 0.5, xe2x80x9cnxe2x80x9d is the weighted average valence of M and has a value of about +1 to about +2, xe2x80x9cpxe2x80x9d is the weighted average valence of R and has a value of +1 to about +2, xe2x80x9cyxe2x80x9d is the mole ratio of Si to (Al+E) and varies from about 5 to about 12 and xe2x80x9czxe2x80x9d is the mole ratio of O to (Al+E) and has a value determined by the equation:
z=(mxc2x7n+rxc2x7p+3+4xc2x7y)/2
the zeolite characterized in that it has at least two x-ray diffraction peaks, one at a d-spacing of 3.9xc2x10.12 xc3x85 and one at 8.6xc2x10.20 xc3x85.
In a particular embodiment, the zeolite catalyst has been designated UZM-5 and has the x-ray diffraction pattern having at least the d-spacings and intensities set forth in Table A:
One specific embodiment involves the alkylation of benzene with propylene to give cumene.
Another embodiment of the invention is a transalkylation process comprising reacting under transalkylation reaction conditions a polyalkylated aromatic compound with a nonalkylated aromatic compound in the presence of the zeolites described above, wherein at least one alkyl group is transferred from the polyalkylated aromatic compound to the nonalkylated aromatic compound.
These and other objects and embodiments will become more apparent after the following detailed description of the invention.
An essential feature of applicants"" process is a new family of zeolites. In its as-synthesized form this family of zeolites has a composition on an anhydrous basis that is represented by the formula:
xe2x80x83Mmn+Rrp+Al(1xe2x88x92x)ExSiyOz
Where M is an exchangeable cation and is selected from the group consisting of alkali and alkaline earth metals. Specific examples of the M cations include but are not limited to lithium, sodium, potassium, cesium, strontium, calcium, magnesium, barium and mixtures thereof. The value of xe2x80x9cmxe2x80x9d which is the mole ratio of M to (Al+E) varies from 0 to 1.2. R is a nitrogen containing organic cation and is selected from the group consisting of pronated amines, protonated diamines, protonated alkanolamines, quaternary ammonium ions, diquaternary ammonium ions, quaternized alkanolammonium ions and mixtures thereof. The value of xe2x80x9crxe2x80x9d which is the mole ratio of R to (Al+E) varies from about 0.25 to about 3.0. The value of xe2x80x9cnxe2x80x9d which is the weighted average valence of M varies from +1 to about +2. The value of xe2x80x9cpxe2x80x9d, which is the average weighted valence of the organic cation has a value from about +1 to about +2. E is an element which is present in the framework and is selected from the group consisting of gallium, iron, chromium, indium, boron and mixtures thereof. The value of xe2x80x9cxxe2x80x9d which is the mole fraction of E varies from 0 to about 0.5. The ratio of silicon to (Al+E) is represented by xe2x80x9cyxe2x80x9d which varies from about 5 to about 12, while the mole ratio of O to (Al+E) is represented by xe2x80x9czxe2x80x9d andxe2x80x9d has a value given by the equation:
z=(mxc2x7n+rxc2x7p+3+4xc2x7y)/2.
When M is only one metal, then the weighted average valence is the valence of that one metal, i.e. +1 or +2. However, when more than one M metal is present, the total amount of:
Mmn+=Mm1(n1)++Mm2(n2)++Mm3(n3)++ . . .
and the weighted average valence xe2x80x9cnxe2x80x9d is given by the equation:   n  =                                          m            1                    ·                      n            1                          +                              m            2                    ·                      n            2                          +                              m            3                    ·                      n            3                          +        …                              m          1                +                  m          2                +                              m            3                    ⁢                      xe2x80x83                    ⁢          …                      .  
Similarly when only one R organic cation is present, the weighted average valence is the valence of the single R cation, i.e., +1 or +2. When more than one R cation is present, the total amount of R is given by the equation:
Rrp+=Rr1(p1)++Rr2(p2)++Rr3(p3)+
and the weighted average valence xe2x80x9cpxe2x80x9d is given by the equation:   p  =                                          p            1                    ·                      r            1                          +                              p            2                    ·                      r            2                          +                              p            3                    ·                      r            3                          +        …                              r          1                +                  r          2                +                  r          3                +        …              .  
The zeolitic compositions are prepared by a hydrothermal crystallization of a reaction mixture prepared by combining reactive sources of R, aluminum, silicon and optionally E and/or M in aqueous media. Accordingly, the aluminum sources include, but are not limited to, aluminum alkoxides, precipitated alumina, aluminum hydroxide, aluminum salt and aluminum metal. Specific examples of aluminum alkoxides include, but are not limited to aluminum ortho sec-butoxide, and aluminum orthoisopropoxide. Sources of silica include but are not limited to tetraethylorthosilicate, fumed silicas, precipitated silicas and colloidal silica. Sources of the M metals include the halide salts, nitrate salts, acetate salts, and hydroxides of the respective alkali or alkaline earth metals. Sources of the E elements include but are not limited to alkali borates, boric acid, precipitated gallium oxyhydroxide, gallium sulfate, ferric sulfate, ferric chloride, chromium chloride, chromium nitrate, indium chloride and indium nitrate. When R is a quaternary ammonium cation, the sources include the hydroxide, and halide compounds. Specific examples include without limitation tetramethylammonium hydroxide, tetraethylammonium hydroxide, hexamethonium bromide, tetramethylammonium chloride, methyltriethylammonium hydroxide. R may also be neutral amines, diamines, and alkanolamines. Specific examples are triethanolamine, triethylamine, and N,N,Nxe2x80x2,Nxe2x80x2 tetramethyl-1,6-hexanediamine.
The reaction mixture containing reactive sources of the desired components can be described in terms of molar ratios of the oxides by the formula:
aM2/nO:bR2/pO:(1xe2x88x92c)Al2O3:cE2O3:dSiO2:eH2O
where xe2x80x9caxe2x80x9d is the mole ratio of the oxide of M and has a value of 0 to about 2, xe2x80x9cbxe2x80x9d is the mole ratio of the oxide of R and has a value of about 1.5 to about 30, xe2x80x9cdxe2x80x9d is the mole ratio of silica and has a value of about 5 to about 30, xe2x80x9ccxe2x80x9d is the mole ratio of the oxide of E and has a value of 0 to about 0.5, and xe2x80x9cexe2x80x9d is the mole ratio of water and has a value of about 30 to about 6000. The reaction mixture is now reacted at reaction conditions including a temperature of about 100xc2x0 C. to about 175xc2x0 C. and preferably from about 140xc2x0 C. to about 160xc2x0 C. for a period of about 12 hours to about 14 days and preferably for a time of about 2 days to about 5 days in a sealed reaction vessel under autogenous pressure. After crystallization is complete, the solid product is isolated from the heterogeneous mixture by means such as filtration or centrifugation, and then washed with de-ionized water and dried in air at ambient temperature up to about 100xc2x0 C.
As synthesized, the zeolites will contain some of the exchangeable or charge balancing cations in its pores. These exchangeable cations can be exchanged for other cations, or in the case of organic cations, they can be removed by heating under controlled conditions. All of these methods are well known in the art.
The crystalline zeolites are characterized by a three-dimensional framework structure of at least SiO2 and AlO2 tetrahedral units. These zeolites are further characterized by their unique x-ray diffraction pattern. The x-ray diffraction pattern has at least two peaks: one peak at a d-spacing of about 3.9xc2x10.12 xc3x85 and one peak at a d-spacing of about 8.6xc2x10.20 xc3x85. To allow for ready reference, the different structure types and compositions of crystalline zeolites have been given arbitrary designation of UZM-h, where xe2x80x9chxe2x80x9d is an integer starting at one and where for example xe2x80x9c1xe2x80x9d represents a framework of structure type xe2x80x9c1xe2x80x9d. That is one or more zeolitic composition with different empirical formulas can have the same structure type xe2x80x9chxe2x80x9d, e.g. xe2x80x9c1xe2x80x9d.
In this respect, the following species can be identified by their x-ray diffraction patterns which have at least the d-spacing and relative intensities set forth in Tables A to C.
The zeolite preferably is mixed with a binder for convenient formation of catalyst particles in a proportion of about 5 to 100 mass % zeolite and 0 to 95 mass-% binder, with the zeolite preferably comprising from about 10 to 90 mass-% of the composite. The binder should preferably be porous, have a surface area of about 5 to about 800 m2/g, and be relatively refractory to the conditions utilized in the hydrocarbon conversion process. Non-limiting examples of binders are aluminas, titania, zirconia, zinc oxide, magnesia, boria, silica-alumina, silica-magnesia, chromia-alumina, alumina-boria, silica-zirconia, etc.; silica, silica gel, and clays. Preferred binders are amorphous silica and alumina, including gamma-, eta-, and theta-alumina, with gamma- and eta-alumina being especially preferred.
The zeolite with or without a binder can be formed into various shapes such as pills, pellets, extrudates, spheres, etc. Preferred shapes are extrudates and spheres. Extrudates are prepared by conventional means which involves mixing of zeolite either before or after adding metallic components, with the binder and a suitable peptizing agent to form a homogeneous dough or thick paste having the correct moisture content to allow for the formation of extrudates with acceptable integrity to withstand direct calcination. The dough then is extruded through a die to give the shaped extrudate. A multitude of different extrudate shapes are possible, including, but not limited to, cylinders, cloverleaf, dumbbell and symmetrical and asymmetrical polylobates. It is also within the scope of this invention that the extrudates may be further shaped to any desired form, such as spheres, by any means known to the art.
Spheres can be prepared by the well known oil-drop method which is described in U.S. Pat. No. 2,620,314 which is incorporated by reference. The method involves dropping a mixture of zeolite, and for example, alumina sol, and gelling agent into an oil bath maintained at elevated temperatures. The droplets of the mixture remain in the oil bath until they set and form hydrogel spheres. The spheres are then continuously withdrawn from the oil bath and typically subjected to specific aging treatments in oil and an ammoniacal solution to further improve their physical characteristics. The resulting aged and gelled particles are then washed and dried at a relatively low temperature of about 50-200xc2x0 C. and subjected to a calcination procedure at a temperature of about 450-700xc2x0 C. for a period of about 1 to about 20 hours. This treatment effects conversion of the hydrogel to the corresponding alumina matrix.
The alkylation and preferably the monoalkylation of aromatic compounds involves reacting an aromatic compound with an olefin using the above described zeoltic catalyst. The olefins which can be used in the instant process are any of those which contain from 2 up to about 20 carbon atoms. These olefins may be branched or linear olefins and either terminal or internal olefins. Preferred olefins are ethylene, propylene and those olefins which are known as detergent range olefins. Detergent range olefins are linear olefins containing from 6 up through about 20 carbon atoms which have either internal or terminal double bonds. Linear olefins containing from 8 to 16 carbon atoms are preferred and those containing from 10 up to about 14 carbon atoms are especially preferred.
The alkylatable aromatic compounds may be selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene, and substituted derivatives thereof, with benzene and its derivatives being the most preferred aromatic compound. By alkylatable is meant that the aromatic compound can be alkylated by an olefinic compound. The alkylatable aromatic compounds may have one or more of the substituents selected from the group consisting of alkyl groups (having from 1 to about 20 carbon atoms), hydroxyl groups, and alkoxy groups whose alkyl group also contains from 1 up to 20 carbon atoms. Where the substituent is an alkyl or alkoxy group, a phenyl group can also can be substituted on the alkyl chain. Although unsubstituted and monosubstituted benzenes, naphthalenes, anthracenes, and phenanthrenes are most often used in the practice of this invention, polysubstituted aromatics also may be employed. Examples of suitable alkylatable aromatic compounds in addition to those cited above include biphenyl, toluene, xylene, ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, etc.; phenol, cresol, anisole, ethoxy-, propoxy-, butoxy-, pentoxy-, hexoxybenzene, etc.
The particular conditions under which the monoalkylation reaction is conducted depends upon the aromatic compound and the olefin used. One necessary condition is that the reaction be conducted under at least partial liquid phase conditions. Therefore, the reaction pressure is adjusted to maintain the olefin at least partially dissolved in the liquid phase. For higher olefins the reaction may be conducted at autogenous pressure. As a practical matter the pressure normally is in the range between about 200 and about 1,000 psig (1379-6985 kPa) but usually is in a range between about 300-600 psig (2069-4137 kPa). The alkylation of the alkylatable aromatic compounds with the olefins in the C2-C20 range can be carried out at a temperature of about 60xc2x0 C. to about 400xc2x0 C., and preferably from about 90xc2x0 C. to about 250xc2x0 C., for a time sufficient to form the desired product. In a continuous process this time can vary considerably, but is usually from about 0.1 to about 3 hrxe2x88x921 weight hourly space velocity with respect to the olefin. In particular, the alkylation of benzene with ethylene can be carried out at temperatures of about 200xc2x0 C. to about 250xc2x0 C. and the alkylation of benzene by propylene at a temperature of about 90xc2x0 C. to about 200xc2x0 C. The ratio of alkylatable aromatic compound to olefin used in the instant process will depend upon the degree of selective monoalkylation desired as well as the relative costs of the aromatic and olefinic components of the reaction mixture. For alkylation of benzene by propylene, benzene-to-olefin ratios may be as low as about 1 and as high as about 10, with a ratio of 2.5-8 being preferred. Where benzene is alkylated with ethylene a benzene-to-olefin ratio between about 1:1 and 8:1 is preferred. For detergent range olefins of C6-C20, a benzene-to-olefin ratio of between 5:1 up to as high as 30:1 is generally sufficient to ensure the desired monoalkylation selectivity, with a range between about 8:1 and about 20:1 even more preferred.
The zeolites of this invention can also be used to catalyze transalkylation. By xe2x80x9ctransalkylationxe2x80x9d is meant that process where an alkyl group on one aromatic nucleus is intermolecularly transferred to a second aromatic nucleus. A preferred transalkylation process is one where one or more alkyl groups of a polyalkylated aromatic compound is transferred to a nonalkylated aromatic compound, and is exemplified by reaction of diisopropylbenzene with benzene to give two molecules of cumene. Thus, transalkylation often is utilized to add to the selectivity of a desired selective monoalkylation by reacting the polyalkylates invariably formed during alkylation with nonalkylated aromatic to form additional monoalkylated products. For the purposes of this process, the polyalkylated aromatic compounds are those formed in the alkylation of alkylatable aromatic compounds with olefins as described above, and the nonalkylated aromatic compounds are benzene, naphthalene, anthracene, and phenanthrene. The reaction conditions for transalkylation are similar to those for alkylation, with temperatures being in the range of about 100 to about 250xc2x0, pressures in the range of 100 to about 750 psig, and the molar ratio of unalkylated aromatic to polyalkylated aromatic in the range from about 1 to about 10. Examples of polyalkylated aromatics which may be reacted with, e.g., benzene as the nonalkylated aromatic include diethylbenzene, diisopropylbenzene, dibutylbenzene, triethylbenzene, triisopropylbenzene etc.
In order to more fully illustrate the invention, the following examples are set forth. It is to be understood that the examples are only by way of illustration and are not intended as an undue limitation on the broad scope of the invention as set forth in the appended claims.